Heretofore, there have been proposed various tires as a safety tire capable of continuously and safely running to a place provided with an equipment for exchanging or repairing the tire even if the internal tire pressure drops or disappears due to the puncture of the tire, damage of an air valve and the like.
As an example of them, there is a tubeless pneumatic tire as shown at a cross section in FIG. 1, in which a hollow, toric air bag 102 made of a soft rubber likewise a tire tube is put in an interior of the tire 101 and a reinforcing layer 103 is arranged on an outer peripheral side of a crown portion of the air bag 102 over a full periphery thereof. Such a safety tire is used by assembling the pneumatic tire 101 onto a standard rim 104 and filling a given air pressure into an interior of the tire through a valve 105 and further filling an air pressure higher than the internal tire pressure into an interior of the air bag 102 through another valve 106.
The term “standard rim” used herein means a rim specified according to a standard of JATMA YEAR BOOK 2000, ETRTO STANDARD MANUAL 2000, TRA (THE TIRE and RIM ASSOCIATION INC.) YEAR BOOK 2000 or the like. As represented by JATMA YEAR BOOK, the standard rim is an approved rim described in its General Information.
In case of running the safety tire under loading in the presence of the given air pressure inside the tire 101, the robbing of the air bag 102 with an inner peripheral face of a tread portion in a ground contact region of a tread can be effectively prevented by the action of the reinforcing layer 103 acting as a member for suppressing a size growth of the air bag 102.
On the other hand, if a pressure difference between an inside and an outside of the air bag 102 exceeds a given value due to the drop, disappear or the like of the internal tire pressure, the air bag 102 is expansion-deformed under an extension deformation of the reinforcing layer 103 to approximately uniformly adhere to the inner face of the tire 101 over its full peripheral and hence the air bag 102 acts as in the conventional tire tube to subrogate a load support from the tire 101 while controlling deflection deformation of the tire to a small extent, whereby a continuous and safe running can be realized in the puncture of the tire or the like.
In the above proposed technique, when the toric reinforced air bag is constructed by integrally vulcanization-joining the reinforcing layer 103 on the outer peripheral side of the air bag 102, if stone or other foreign matter entered, for example, from a punctured hole of the tire into the interior of the tire sticks in, butts onto or rubs with the reinforcing layer 103 to create cracks in the reinforcing layer 103, there is a problem that a fear of prematurely propagating such cracks to the air bag 102 integrally united with the reinforcing layer 103 is high.
Also, in order to produce the toric reinforced air bag by integrally uniting the reinforcing layer 103 with the air bag 102 through vulcanization, it is necessary that a starting material for the reinforcing layer is applied onto an outer peripheral face of an uncured air bag having an unstable shape over a given region while suppressing an expansion shape of the uncured air bag as is expected, if necessary, and both the materials are joined through vulcanization, so that there is finally caused a problem that it is difficult to accurately arrange the reinforcing layer 103 on a given position of the air bag 102.
The invention is made for solving the above problems of the conventional techniques and is to provide a toric reinforced air bag for a safety tire capable of effectively preventing the propagation of cracks to the air bag even if the cracks or the like are created in the reinforcing layer and a method of producing a toric reinforced air bag for a safety tire in which a reinforcing layer can be accurately produced in desired shape, size and the like and also such a reinforcing layer can be simply and easily fitted onto a desired position of a toric air bag.